The Contractor shall participate in a randomized controlled trial to evaluate screening for prostate cancer using original rectal examination and prostate-specific antigen, screening for lung cancer using chest x- ray, screening for colo-rectal cancer using digital rectal examination and flexible sigmoidoscopy and screening for ovarian cancer using CA 125, transvaginal sonography, and pelvic examination. The Trial protocol was developed during the pilot phase of the Trial, 1992-1995. the contractor shall implement the Trial tasks according to the protocol in the PLCO Cancer Screening Trial manual of Operations and Procedures (MOOP). 1. Identification, entry into the study, nd randomization of at lest 5,000 subjects aged 55-74 into a screened group of 2500 or more individuals. 2. Determination of participant eligibility and baseline characteristics. 3. Obtain local IRB approval for Trial implementation before participant enrollment or randomization to the Trial. 4. Assessment of background level of usage and trend in usage of each screening modality by appropriate surveys in the screening center's catchment region. 5. Provision of screening tests for all four cancer sites. 6. Provision of or referral for diagnostic workups for individuals designated positive by one or more of the screening tests. 7. Provision of cancer incidence and vital status follow-up events for those individuals diagnosed with cancer. 8. Provision of cancer incidence and vital status follow-up procedures for all randomized individuals to determine all instances of cancer diagnosis whether by screening or otherwise. 9. Ascertain all deaths and cause of death. 10. Administration of the study.